1. Field of the Invention
The invention relates to a semiconductor device, in particular, a semiconductor device having a semiconductor die mounted on a lead frame.
2. Description of the Related Art
In a semiconductor device having a plurality of semiconductor dies such as an IC die, as shown in FIG. 6, for example, an IC die 110A is bonded to an island 150 of a lead frame made of metal such as copper through a conductive paste 140.
A semiconductor device having a semiconductor die mounted on a lead frame is disclosed in Japanese Patent Application Publication Nos. 2010-80914 and 2006-32479, for example.
However, depending on the purpose of use of a semiconductor device, as shown in FIG. 6, a surge (a pulse-shaped overvoltage having a high leading edge of an amplitude) tends to be applied thereto through a pad electrode 111 disposed on the front surface of the IC die 110A. For example, when the semiconductor device is an igniter controlling an ignition plug on a vehicle, a large surge tends to be applied thereto due to noise occurring at other peripheral device on the vehicle such as a motor.
Depending on the amount of a surge, a surge current flowing from the pad electrode 111 into the semiconductor substrate 110 may reach the back surface of the semiconductor substrate 110 and cause dielectric breakdown. Then heat generated at the time may cause the semiconductor substrate 110 to crack, thereby breaking the igniter.